Field emission displays ("FEDs") are flat panel displays for use in computers, television sets, instrument displays, camcorder view finders and a variety of other applications. FEDs generally have a faceplate with a glass panel, a substantially transparent anode covering an inner surface of the glass panel, and a cathodoluminescent film covering the anode. FEDs also have a baseplate with an emitter substrate and an extraction grid. As described below, the faceplate and baseplate are generally spaced apart from one another so that the cathodoluminescent film is juxtaposed to the emitter substrate and the extraction grid.
FIG. 1 illustrates a portion of a conventional FED baseplate 20 with an emitter substrate 30 that carries a plurality of emitters 32. The emitter substrate 30 also carries a dielectric layer 40 with a plurality of cavities 42 around the emitters 32, and the dielectric layer 40 supports a conductive extraction grid 50 with a plurality of holes 52 over the emitters 32. The cavities 42 and the holes 52 expose the emitters 32 to the cathodoluminescent film on the faceplate (not shown).
FIG. 2 is a top schematic view of the baseplate 20 that illustrates one technique for extracting electrons from selected emitters. The emitters 32 may be grouped into discrete emitter sets 33 configured in rows (e.g., R.sub.1 -R.sub.3) and columns (e.g, C.sub.1 -C.sub.2). A number of high-speed row interconnects 55 on the extraction grid 50 commonly connect a plurality of emitter sets 33 along row address lines, and a number of high-speed column interconnects 37 on the emitter substrate 30 commonly connect emitter sets 33 along column address lines. As best shown in FIG. 1, the row interconnects 55 are formed on top of the extraction grid 50 and the column interconnects 37 are formed beneath the extraction grid 50. It will be appreciated that the row and column assignments illustrated in FIGS. 1 and 2 are for illustrative purposes only, and that other row/column assignments may be implemented in field emission displays.
To operate a specific emitter set 33, drive circuitry (not shown) generates row and columns signals along the coordinates of the specific emitter set 33 to create a voltage differential between the extraction grid and the specific emitter set. Referring to FIG. 2, for example, a row signal along row R.sub.2 of the extraction grid 50 and a column signal along column C.sub.1 of the emitter substrate 30 activates the emitter set 33 at the intersection of row R.sub.2 and column C.sub.1. The voltage differential between the extraction grid 50 and the selected emitter set 33 produces a localized electric field that extracts electrons from the emitters 32 in the selected emitter set. The anode on the faceplate then attracts the extracted electrons across a vacuum gap between the extraction grid and the cathodoluminescent layer. As the electrons strike the cathodoluminescent layer, light emits from the impact site and travels through the anode and the display screen. The emitted light from each area becomes all or part of a picture element.
Constructing FEDs raises several manufacturing issues that are best understood in light of the relationship between the baseplate and the faceplate. FIG. 3 is an exploded schematic cross-sectional view of a conventional FED 10 with the baseplate 20 and a faceplate 60. In addition to the components described above in FIGS. 1 and 2, the baseplate 20 also has a plurality of bond pads 36 in or on the emitter substrate 30 such that each bond pad 36 is coupled to an end of a column interconnect 37 to provide contact points for the drive circuitry of a particular column of emitter sets 33. The faceplate 60 has a transparent substrate 62, an optically transmissive anode 64 covering the transparent substrate 62, and a cathodoluminescent film 66 covering the anode 64. The faceplate 60 also has spacers 63a and 63b on opposite sides of the anode 64 and the cathodoluminescent film 66. A number of leads 80 (only one shown on each side) coupled to the drive circuitry (not shown) extend to the spacers 63a and 63b, and each lead 80 has a connector pad 82 and a raised feature 84 positioned on one of the spacers 63a or 63b. The raised features 84 are formed in a pattern corresponding to the pattern of bond pads 36 in the baseplate 20. The leads 80 and connector pads 82 are typically aluminum traces having a thickness of 12-20 .mu.m, and the raised features 84 are typically 20-50 .mu.m points formed by individually pinching the aluminum of the connector pads 82.
One particular manufacturing concern is that attaching the baseplate 20 to the faceplate 60 is a time-consuming and labor intensive process. For example, because the raised features 84 are formed individually by pinching the connector pads 82, it takes a significant amount of time to form all of the raised features 84. Moreover, because the bond pads 36 are typically quite small and spaced very close to one another, some of the raised features 84 may not align with a corresponding bond pad 36 when the baseplate 20 and the faceplate 60 are juxtaposed to one another. Such misalignment between the bond pads 36 and the raised features 84 may accordingly damage the baseplate 20 or severely impair the performance of the FED when the faceplate 60 is attached to the baseplate 20. Many FEDs 10, therefore, must be tested individually and either repaired or thrown-away. Thus, forming the raised features 84 is a problematic aspect of constructing FEDs.